/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlineGroupsInterface.h
Get the cached Roster (membership) information for a group. If the information is not cached locally, call QueryGroupRoster to request it from the server. If the context user is a member of this group, the cached roster information will include petitioners and invitees, otherwise it will not.
Shared pointer to the cached roster structure if one exists
[TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< const [IGroupRoster](API\Plugins\OnlineSubsystem\Interfaces\IGroupRoster) > GetCachedGroupRoster ( const [FUniqueNetId](API\Runtime\CoreOnline\Online\FUniqueNetId) & ContextUserId, const [FUniqueNetId](API\Runtime\CoreOnline\Online\FUniqueNetId) & GroupId )